Power transmission systems are used to selectively deliver rotational power from a driver device such as an internal combustion engine, electric motor or other source of rotational power, to a driven device. Driven devices may commonly include such things as pumps, electric generators, the tires of a vehicle or the propeller of a watercraft. Clutches are used to selectively operatively engage and disengage the driver from the driven device.
Mechanical clutches commonly operate to selectively engage and disengage the driver and driven devices by having a stack of adjacent clutch discs. The discs in the stack which is also referred to herein as a disc pack, are alternatively mechanically operatively engaged with driving and driven members. The axial force that acts between the discs can be selectively varied. When the clutch is not engaged, the discs that move with the driving member are sufficiently movable relative to the discs that are engaged with the driven member such that they can rotate relative thereto. To engage the clutch, the discs in the stack are axially compressed such that the discs connected to the driving member are in pressurized abutting engagement with the discs connected to the driven member. As a result, the driven member is caused to rotate with the driving member, and the driven device is engaged with the driver.
High friction material is often attached to the discs to provide enhanced frictional engagement when the clutch is engaged. Releasing the axial compression force causes the discs to again be able to rotate relative to one another and the clutch is disengaged. Springs or similar mechanisms can be positioned to act on the discs to facilitate the discs sufficiently separating to disengage the clutch when the axial compression force is released.
Mechanical clutches commonly experience certain types of issues which limit their capabilities and useful life. These include wearing of the clutch discs over time with repeated engagement and disengagement of the clutch. Other issues may include providing sufficient axial force to the discs in order to transmit the level of power needed to operate the driven device. Other issues include avoiding excessive heat which can shorten the life of clutch discs and also limit power transmission capabilities. Other issues include shock and jarring which can damage driven devices when clutches are rapidly engaged. Other issues include damage to clutch components when the clutch is operated in a slipping mode for an extended period of time. Additional problems and drawbacks can be encountered with mechanical clutches and systems depending upon the particular system in which a clutch is used.
Mechanical clutches and related systems may benefit from improvements.